I have four rotary tools and two of them are cordless without cases. As a result, it makes keeping the tool and tool heads together as the boxes are getting shop-worn. I have found cases, but the heads are scattered to and fro now. I am of the mindset of never having enough tools. This bag of tool heads will replace the missing ones that I will find once I clear out my garage. My only complaint is that everything came in a bag instead of hard stiff container. The result is some (not all) broken disks. The tools seem to be of the same quality as all of the ones that came with my rotaries. I was able to tackle a minor adjustment to a part that was so close to fitting. I used the sharp pointed tip to file it to the right depth. I will be using them to help me clean up my 3D prints.